Such blood bag system for fractionating blood usually consists of a first collecting bag used for collecting whole blood and one or more sub-bags used for fractionating blood into separated blood products. Plastic tubing couples said bags together to form a so-called closed multiple blood bag system. Typical system comprises four or five blood bags in fluid communication such that once whole blood is introduced into the system, the whole blood or its components may be moved from one bag to another by external manipulation of valves, and the like, thereby avoiding contamination. Depending on the configuration, the blood bag system may also include a white blood cells removing filter, downstream the whole blood bag.
In a typical multiple blood bag system application, whole blood is collected into a first bag and all connected blood bags, which are usually empty, are placed in a centrifuge. The bag contents are then centrifuged to separate whole bloods into its components (see FIG. 1A). By manipulating a valve, which is typically a frangible valve within the system, the blood products of the whole blood may then be transferred into one of the others blood bags, possibly for further processing. Said blood products may be red blood cell concentrate (hereinafter referred to as RBC), platelet concentrate (hereinafter referred to as PC), blood plasma (hereinafter referred to as BP) including category 1 and category 2 blood plasma, or the like.
Centrifugation of whole blood in typical blood processing raises several issues. The high rotation speed allows stratification of the whole blood (see FIG. 1B) but also induce strong shear on the cells thereby activating PC. Due to centrifugation of the whole blood, between 20 to 40% of the platelets collected may indeed be activated. It strongly affects the efficiency of the PC when injected to a patient and also reduce its storage time to no more than 5 days. Other blood products, such as RBC, may also be affected by the high rotation speed. Furthermore, fractionation of whole blood by centrifugation lasts up to 7 hours and requires several manuals steps and at least two centrifugations.
The present invention aims at overcoming the drawbacks of the prior art by providing a method for preparing all kinds of blood products and an easy-to-use, closed, disposable, sterile, multiple blood bag system enabling production of all the blood products within a single system, limiting manual operations and also avoiding any centrifugation step.